Monoclonal antibodies (MAbs) have defined several antigens associated with human carcinomas. Two of the most widely studied antigens are carcinoembryonic antigen (CEA) and TAG-72. CEA is a 180 kD glycoprotein and TAG-72 is a high molecular weight mucin. Recent studies have demonstrated that CEA is a member of the immunoglobulin supergene family. These include CEA, normal cross-reacting antigen (NCA), biliary glycoprotein (BGP), and human pregnancy-specific beta 1-glycoprotein (SPl). The use of anti-CEA MAbs for diagnosis and therapy have been explored by a number of labs. In order to assess the ability of CEA to serve as a target for active immunotherapy, a mouse model has been generated in our lab. Mouse tumor cell lines expressing high levels of CEA have been derived, and the characteristics of the expressed gene products have been analyzed. These tumor cells have been shown to grow in immunocompetent mice, and in preliminary experiments have shown to serve as targets for active immunotherapy, carried out with a CEA-vaccinia construct (see project #Z01 CB 09028-02). Experiments in other systems have demonstrated the ability of purified proteins produced in a baculovirus system, to boost responses to recombinant proteins produced in vaccinia. Recently, experiments have begun to explore the use of the baculovirus system for production of recombinant CEA.